The “Anthropocene Working Group” has proposed that 1952, two years after my birth, be designated the end of the Holocene geologic epoch and the dawn of a new epoch, the Anthropocene, dominated by human impacts. While the AWG has selected the radioisotope plutonium from nuclear bomb testing as the marker of the epochal transition, other groups have proposed the global spread of persistent organic pollutants, POPs, as a second category, this one including pesticides and plastics (Zalasiewicz, Waters et al. 2016). This new epoch is not official, at least not until it is affirmed by the International Union of Geological Sciences. Yet those of us who have lived through the seven decades of enormous changes in population, nutrient releases, climate change, and POPs may find it hard to deny that humanity has created a new epoch.
I believe my body is a marker of the Anthropocene. It likely carries a large share of POPs. My mother was an early adopter of all things labeled Scotchgard, and she dressed me in plastic-based Perma-press clothing. My father drizzled chlordane along the house foundation for ant control and probably doused the yard with DDT for mosquito control. I remember a small can of carbon tetrachloride we used for stain removal. Might my exposures to such POPs have relevance to my health today, say, perhaps my cancer? It is not for me to know.
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Is a lifetime of exposure to POPs a health issue for us “sentinels”? CDC asked that very question of its national health and mortality database for folks in my age group. The 2017 report of this evaluation is Persistent organic pollutants and mortality in the United States, NHANES 1999–2011. The report explains: “Analyses included participants aged 60 years and older from the 1999–2006 National Health and Nutrition Examination Surveys (NHANES). We included 483 participants for analyses of PBDEs, 1043 for PFASs, and 461 for PCBs, and 1428 for OC pesticides. Exposures to POPs were estimated using biomarkers measured in serum.”
My age is at the center of the cohort of this CDC study, so I was mostly relieved by the results. The report concludes: “Our study found that serum measurements of PBDEs, PFASs, and PCBs are not clearly associated with increased mortality in the U.S. population aged 60 years or older. β-hexachlorocyclohexane, an OC pesticide, was associated with an increased risk of all-cause mortality. All four OC pesticides detectable in >90% of the sample (oxychlordane; p,p’-DDE; Trans-nonachlor; and β-hexachlorocyclohexane) were associated with increased risk of other-cause (non-cancer, non-cardiovascular) mortality. (Fry and Power 2017).” I underscore the finding that PFAS is not associated with increased mortality. Phew!
We seniors are significant sentinels of POP impacts (Jones 2021). Perhaps we deserve to be more seriously studied, as we are likely the “worst case” for most POPs that are today the focus of current regulatory concern, including the focus on PFAS compounds. At my death, perhaps I should donate my body to PFAS science.
The pesticide POPs called out by CDC have been banned. So how is it that these POPs are still in the blood samples of folks my age? The NHANES database shows that even when POP use ends, POPs continue to show up in human blood fifty years after their bans. POPs such as PCBs, chlordane, and DDT really do persist in the environment, getting into food and water and getting into the human body, albeit at far lower levels than decades ago.
If such banned POPs can still appear in human blood, what about those POPs like PFAS and plastics that have not yet been fully banned and are still in use?
Maybe we don’t have to worry about plastics in our bodies. The risks to human health of microplastics is generally believed to be low. Copilot tells me microplastics are “not yet quantifiably dangerous.” But will that always be true? Evidence to the contrary is starting to appear. One recent article, Microplastics in the Olfactory Bulb of the Human Brain, discusses how micro and nanoplastics have a pathway to the brain through the olfactory nerves (Amato-Lourenço, Dantas et al. 2024), potentially interfering with energy transfer in the brain cell mitochondria.
Plastic is a POP that seems irreplaceable in today’s economy. Plastics are highly unlikely to be banned from human use, even if health risks are confirmed. Does this situation arise with other POPs, ones too important to ban, even in the face of health effects?
Of course, I am leading to the issue of PFAS. Researchers are finding PFAS in soil, water and air in every corner of the globe. It is no surprise that PFAS compounds occur in biosolids everywhere. Some large-volume PFAS compounds were voluntarily withdrawn from many consumer commodities in 2002. Consequently, PFAS concentrations in human serum are also down, as are, happily, concentrations in biosolids. But unlike PCB and DDT, PFAS use has not ended, as some uses, e.g., firefighting, seem too important. So, PFAS contamination of biosolids will not go away. Long-chain fluorinated compounds may have been replaced by short-chain compounds, but wastewater processes are no better at degrading short-chain compounds than long-chain ones, so short-chains may show up in the biosolids, too, when measured. What is more, substitution of alternative fluorinated compounds for regulated PFAS compounds may not result in reduced PFAS risks to humans. Yet, EPA just announced it is backing down from proposed regulations (E.P.A. to End Some Limits on ‘Forever Chemicals’ in Drinking Water), even though groups such as the Environmental Working Group oppose this action (FDA Studies: ‘Short-chain’ PFAS Chemicals More Toxic Than Previously Thought).
How are we to frame today’s issues around managing biosolids-borne PFAS when this issue is viewed against policies that permit continued use of fluorinated compounds? Why regulate PFAS in biosolids when there is growing evidence of risks from other significant PFAS exposure pathways? Why regulate PFAS in biosolids when other POPs, like regulated pesticides and unregulated antibiotics and microplastics, may be no less risky? From this framing, regulating biosolids for PFAS seems more of a response to political and media pressure than a response to genuine health risks.
One important factor in issue framing is the high costs in capital and time necessary to mitigate PFAS in biosolids. Land application, a low-cost option for biosolids, is relied upon by thousands of public treatment works, as land application has been for four decades a cornerstone of biosolids management. PFAS emerged only recently in 2019 as a potentially existential threat to the architecture of national biosolids policies and regulations. Some biosolids experts have argued that PFAS concentrations at any level in biosolids warrant ending land application practices. But this is not a workable direction for many utility managers who need to balance public health risks of PFAS in biosolids with predicted costs for PFAS treatment technologies. For many utilities, continued viability of land application is necessary, at least for the foreseeable future.
I argue that land application will continue to be an environmentally responsible option. Risks of biosolids-borne PFAS are not uniform across agencies and land application sites. Locations around the U.S. with seriously elevated PFAS contamination are not the norm for land application programs and occur relatively infrequently (Pepper, Brusseau et al. 2025). PFAS-contaminated WRRFs have been uncovered, for example, in Maine, Michigan, and Georgia, where treatment works were impacted by high industrial discharges of PFAS-laden residuals (Carlson and Andersen 2025). High influent PFAS loadings, whether from WRRFs or from manufacturing, fire training facilities, or other sites, have been relatively manageable when discovered and treated (Helmer, Reeves et al. 2022). But for the very large proportion of WRRFs, PFAS concentrations in biosolids are traceable to normal urban activities and consumer product sources (Lin, Méndez et al. 2024). Several state regulators have concluded that background PFAS concentrations pose no significant human or environmental impacts when biosolids are land applied at agronomic rates.
The viability of PFAS treatment technologies available today to WRRFs is a key concern. Thermal technology solutions to PFAS-contaminated biosolids may not work, or may not work consistently, or may not work cost-effectively (Ling, Vermace et al. 2024). Perhaps technologists are close to showing effectiveness, but not with a track record of full-scale operations, at least not today (Samberger, Palmer et al. 2025). Utility managers are generally very cautious in adopting technologies that are not proven for reliable performance, as managers often have no real choice but to install dependable equipment.
In the absence of a technological solution to PFAS trapped in wastewater solids, we need to return to the question of “just how bad is the risk of PFAS in biosolids?” When set against other pathways of PFAS exposure and against other POPs, the answer to that question is “not bad enough to abandon land application.” Wastewater managers have huge challenges for managing wastewater pollutants and must remain focused on responsibly balancing treatment costs against health risks.
Amato-Lourenço, L. F., K. C. Dantas, G. R. Júnior, V. R. Paes, R. A. Ando, R. de Oliveira Freitas, O. M. M. M. da Costa, R. S. Rabelo, K. C. Soares Bispo, R. Carvalho-Oliveira and T. Mauad (2024). “Microplastics in the Olfactory Bulb of the Human Brain.” JAMA Network Open 7(9): e2440018–e2440018.
Carlson, G. L. and M. Andersen (2025). “Tracking environmental contamination from multiple sources of per- and polyfluoroalkyl substances.” Environmental Research 276: 121470.
Fry, K. and M. C. Power (2017). “Persistent organic pollutants and mortality in the United States, NHANES 1999–2011.” Environmental Health 16(1): 105.
Helmer, R. W., D. M. Reeves and D. P. Cassidy (2022). “Per- and Polyfluorinated Alkyl Substances (PFAS) cycling within Michigan: Contaminated sites, landfills and wastewater treatment plants.” Water Research 210: 117983.
Jones, K. C. (2021). “Persistent Organic Pollutants (POPs) and Related Chemicals in the Global Environment: Some Personal Reflections.” Environmental Science & Technology 55(14): 9400–9412.
Lin, D., M. Méndez, K. Paterson, A. Wong, D. Yee, R. Sutton, E. Houtz, M. Cousins and L. Fono (2024). “Residential Wastewater as a Major Source of Per- and Polyfluoroalkyl Substances to Municipal Wastewater.” ACS ES&T Water 4(11): 4847–4857.
Ling, A. L., R. R. Vermace, A. J. McCabe, K. M. Wolohan and S. J. Kyser (2024). “Is removal and destruction of perfluoroalkyl and polyfluoroalkyl substances from wastewater effluent affordable?” Water Environment Research 96(1): e10975.
Pepper, I., M. Brusseau, S. Prasek, J. Chorover and G. Kester (2025). “NATIONAL COLLABORATIVE STUDY ON THE INCIDENCE AND MOBILITY OF PFAS FOLLOWING LAND APPLICATION OF BIOSOLIDS.”
Samberger, C., S. Palmer, A. Umble, O. Joan and J. Jacangelo (2025). Challenges and solutions of municipal biosolids market creation: a critical review.
Zalasiewicz, J., C. N. Waters, J. A. Ivar do Sul, P. L. Corcoran, A. D. Barnosky, A. Cearreta, M. Edgeworth, A. Gałuszka, C. Jeandel, R. Leinfelder, J. R. McNeill, W. Steffen, C. Summerhayes, M. Wagreich, M. Williams, A. P. Wolfe and Y. Yonan (2016). “The geological cycle of plastics and their use as a stratigraphic indicator of the Anthropocene.” Anthropocene 13: 4–17.